1. Field of the Invention
The present invention relates to a means and method for protecting maturing fruits and vegetables from low temperature and, more particularly, is concerned with thermally insulating maturing fruits and vegetables during soft freeze utilizing a water and air permeable bag with an elasticized opening.
2. Description of Related Art
Many types of fruits and vegetables cultivated outdoors are susceptible to damage from low surface temperature of the air. For example, freezing temperatures (32.degree. F., 0.degree. C. and below) can destroy maturing citrus fruits such as oranges, lemons, and grapefruits that are not protected.
Two techniques are commonly used to protect susceptible fruits and vegetables from low temperatures. First, large commercial growers may employ auxiliary heating means such as smudge pots to protect their crops. However, the initial capital investment and operating expenses for such systems may prove cost prohibitive to noncommercial growers as well as small commercial growers such as small nurseries. Furthermore, the use of such systems requires growers to be aware of impending low temperatures in order to initiate system operation in anticipation of a drop in temperature. Being on constant alert to the threat of low temperature may prove overly bothersome for many noncommercial growers.
A second technique for protecting susceptible fruits and vegetables from low temperatures involves covering the entire parent plant with a thermally insulating material, such as cardboard, plastic, or wood. While this technique is inexpensive and therefore more accessible to small nurseries and noncommercial growers, it suffers several drawbacks.
One drawback to protecting fruits and vegetables using parent plant coverings is the impracticality of using a cover for a large plant. While growers may cover small- to moderately-sized plants such as tomato plants in anticipation of low temperatures, covering large plants such as tall trees or plants with many branches would likely be impractical and inefficient. Growers without smudge-pot capabilities may therefore be without a means of protecting fruit and vegetables maturing on large plants. A second drawback to parent plant coverings as a technique is the requirement that the grower devote careful attention to weather forecasts. Just as in the case of smudge-pot systems, the grower must be aware of impending low temperatures in order to provide timely protection to susceptible fruits and vegetables. Because such coverings likely inhibit water and light transmission to the parent plant, growers optimally leave the coverings in place only during periods of potentially damaging low temperatures.
In addition to the more common techniques of thermally protecting maturing fruits and vegetables by heating or insulating the entire parent plant, several patents disclose protection systems geared toward individual fruits and vegetables. For example, U.S. Pat. No. 383,327, "Envelope for Protecting Grapes While Maturing", discloses a translucent water-proof envelope that is fastened around grapes using clamps or other suitable fastening devices. The corners of the envelope are turned down to prevent the entrance of foreign materials, and perforations in the bottom and sides of the envelope permit drainage of any water that may enter. While the envelope likely provides effective thermal protection for bunches of grapes, the shape of the envelope is not optimal for protecting spherically-shaped fruits such as oranges and grapefruits. Furthermore, securing the envelope around the grapes requires considerable effort from the grower in the manipulation of fasteners and flaps.
U.S. Pat. No. 3,630,758, "Fruit Harvesting Technique", is directed to a fruit harvesting technique for apples. This method comprises coating the apples in situ on the tree with a cushioning material, preferably a polymer froth foam. The foam is designed to cushion the fruit to prevent damage by physical contact during harvest, handling, and storage, not to thermally insulate the fruit to prevent damage by low temperatures. Furthermore, in the event that this technique could be adapted to thermally insulate fruits and vegetables, noncommercial growers would likely find this technique to be inconvenient. First, the fruit or vegetable would require complete coverage by the foam for effective insulation, making application of the foam tedious and time-consuming. Second, additional applications of the foam may be required, depending on the adherence of the foam to the fruit or vegetable. Third, extensive clean-up efforts may be necessary for the area surrounding the parent plant once the foam has been applied.
U.S. Pat. No. 4,159,596, "Means and a Method for the Self-Pollination of Corn", discloses using a single bag for the self-pollination of corn, such that the upper end of the bag encloses the corn plant tassel and the lower end of the bag encompasses the corn plant shoot. The shape of the bag is elongated and tubular, so that the bag would be an improper shape for containing spherically-shaped fruits such as oranges and grapefruits. Moreover, securing the bag around the corn entails considerable effort by the grower in light of various flaps requiring attention.
U.S. Pat. No. 4,698,226, "Apple Labeling Process", incorporates a single weatherproof bag structure which covers the fruit while still attached to the tree. The surface of the bag does not transmit light, so that the natural color of the apple's skin does not develop until the desired step in the labelling process. The shape of the bag is not globular but oblong with a straight bottom edge, so that the bag does not closely surround the fruit as would be optimal for thermal insulation. The relative difficulty of placing the bag on the fruit cannot be evaluated since the patent did not disclose the type of closure mechanism for the bag.
Thus, a need remains for a means and method of protecting maturing fruit and vegetables from low temperature damage in the following two situations: (1) if auxiliary heating means are unavailable and covering the parent plant proves impractical, and (2) if the grower intends to leave the thermal protection in place for extended periods of time in lieu of anticipating low temperatures. Regarding protecting fruit and vegetables on an individual basis, a need remains for a structure that accommodates a broad range of spherically- and elliptically-shaped fruits and vegetables in a more tailored fit than an envelope or oblong structure. Finally, a need remains for a structure that is easily secured around the individual fruit or vegetable.